Many reprographic and/or electrostatographic image-forming devices, such as copiers, facsimile apparatus, printers, and the like include a replaceable or refillable material supply module. The material supply module is typically connected to such a device via a drive shaft and gear shaft coupling arrangement, which generally includes a drive shaft integral to the module that interacts with a gear shaft integral to the particular device.
FIG. 1 shows a drive shaft and gear shaft coupling arrangement 20, which is currently used in the material supply module of copiers, facsimile apparatus, printers, and similar electrostatographic image forming devices. A drive gear 22 drives a driveshaft cylinder 24 of a drive shaft 25. Drive gear 22 includes a gear shaft 26 at its center and a geared outside edge 28. Gear shaft 26 has a front surface 30, which includes a twisted triangular coupling hole 32 having defined vertices 33 formed therein. Driveshaft cylinder 24 is fixedly mounted with a cylinder flange 34, which includes an axially outwardly extending concentric shaft 36 and a geared outside edge 38. Concentric shaft 36 includes an axially outwardly twisted, triangular coupling member 40, which is axially raised from an outer, or front, surface 42 of the shaft 36 for coupling to the twisted triangular coupling hole 32 on gear shaft 26 of drive gear 22.
During the life of a device, driveshaft cylinder 24 and drive shaft 25 may be replaced one or more times depending on the frequency of use. Typically, the cylinder flange 34 is replaced when the driveshaft cylinder 24 and the drive shaft 25 are replaced. Because twisted triangular coupling member 40 of cylinder flange 34 generally twists in one direction and its torque forces are adjacent its axis of rotation, its fabrication is both complicated and expensive. In addition, because the torque forces acting on twisted triangular coupling member 40 of cylinder flange 34 are adjacent its axis of rotation, the member encounters high stresses.
FIGS. 2 and 3 show another coupling arrangement, or mechanism, including a driven coupling 50 and a driving coupling 60. The driven coupling 50 includes a cylinder flange 51 with a geared outside edge 52 and an axially outwardly extending concentric shaft 54. A twisted triangular-shaped coupling member 55 extends axially outwardly from an outer surface 53 of the shaft 54. Coupling member 55 has defined therein a central bore 57 that is configured to receive a locator or alignment pin 64 of the driving coupling 60.
With reference to FIG. 3, driving coupling 60 may be positioned in a conventional reprographic device and includes a stationary outer bushing 61 encasing a rotatable and retractable machine drive 62. Machine drive 62 has a socket 67 therein that is complementary to the shape of coupling member 55. The locator or alignment pin 64 is generally conical in shape and is centered within the machine drive 62 so as to mate with the central bore 57 in the coupling member 55. Locator pin 64, which is generally truncated, has freedom to move in the axial direction and is intended to ensure centering of the driven coupling 50. Engagement of the driven and driving couplings constituting the coupling mechanism initially requires a minimal axial engagement, as the two couplings are forced together into complete engagement by virtue of the torque. However, here, too, because the torque forces acting on triangular coupling member 55 are adjacent its axis of rotation, the member encounters high stresses.